Art of cracking hydrocarbons



May 22, 1934. w. SLGULLETTE' ,9 5 2? ART OF CRACKING HYDROCARBONS Filed Dec". 16, 1929 ATTORNEYS .atented May 22, 1934 1 Claim.

cracking of heavier and higher boiling hydrocarbon oils for the production of lighter and lower boiling hydrocarbon oils in operations in which the heavier or higher boilingoil is heated to a high cracking temperature while in the vapor phase.

The invention is of special value and application in conjunction with operations of the type described in an application filed June 13, 1927, Serial Number 198,621, by Harry L. Pelzer, but the invention is also useful in broader application.

The invention provides particularly an improved operation in which corresponding constituents of raw stocks and recycled stocks are subjected to cracking conditions particularly ad-' vantageous'with respect to the particular con- .stituent and in which conditions in the operation are nevertheless maintained continuously univ form.

According to this invention, two separate streams of oil are flowed through two separate heating conduits and separately heated to high cracking temperatures in the vapor phase therein, 5 the oil stream flowing through one of the heating conduits being heated to a higher temperature therein than is the oil stream flowing through the other heating conduit, the hot oil products discharged from these two heating conduits are subjected to a common scrubbing operation for the separation of tar and separated tar is discharged from this scrubbing operation, none of the discharged tar being returned as such to the heating conduits, the vapors from the scrubbing operation are subjected to successive first and second fractionating operations in which constituents heavier or higher boiling than suitable as components of the desired product are condensed to form a relatively higher boiling high .0 boiling condensate in the'iirst and a relatively lower boiling high boiling condensate in the second, a cracked distillate product is condensed from the vapors escaping from the second fractionating operation, condensate from the second i5 iractionating operation is supplied to the heating conduit in which the oil stream is heated to the higher temperature and condensate from the first fractionating operation is supplied to the other of the two heating conduits. The condensates separated in the two fractionating operations may include, as will appear, together with constituents condensed from the hot oil productsdischarged from the heating conduits constituents of corresponding boiling range of raw stocks supplied to the operation. The condensate of rela- AM or 'oaaomc 'aooAaBoNs Willis S. Gullette, Highland, Ind assignor to Sinclair Refining Company, New York, N. Y., a corporation of Maine Application December 16, 1929, Serial No. 414,333

, (m. 196- -61) This invention relates to'improvements in the tively higher boiling range, including the constituents within this boiling range produced in both heating operations, is thus subjected to conditions more appropriate to the cracking of these higher boiling high boiling constituents while' the condensate of relatively lower boiling range, in-

cluding the constituents within this boiling range produced in both heating operations, is also subjected to conditions more appropriate to the cracking of these lower boiling high boilingcon- 65 stituents, while at the same time, by dividing the heating operations as just described, the conditions in each of the separate heating operations may be maintained continuously uniform over prolonged periods of time although the conditions in the separate heating operations may differ one from the other. v

The invention will be further described in connection with the accompanying drawing which i1- lustrates, diagrammatically and conventionally, in elevation and partly in section and with parts broken away, one form of apparatus adapted ior carrying out the process of the invention.

The apparatus illustrated comprises a pair or. heating conduits 1a and lb arranged in heating so furnaces 2a and 2b, a common scrubbing tower 3, a first fractionating tower 4 and a second fractionating'tower 5, a treating tower 6, another fractionating tower 7, and a condenser 8 and a receiver 9. Oil is supplied to the heating con- 5 duit 1a through connection 10 and to the heating conduit 1b through connection 11, the hot oil products from the heating conduits la and lb are discharged into the scrubbing tower 3 through connections 12a and 12b respectively, tar is discharged from the scrubbing tower 3 through con nection 13, vapors escaping from the scrubbing tower 3 through connection 14 pass successively through the fractionating tower 4, connection 15 and the fractionating tower 5, the vapors escaping from the fractionating tower 5 may pass directly to the condenser 8 or to this condenser through the treating tower 6 and the fractionating tower '7, and. the cracked distillate product is discharged from the receiver 9 through connection 16. y

In general the cracking operation may be carried out as described in application Serial Number 198,621, mentioned above. As illustrated, however, the digesting drums there described may be omitted and the hot oil products from the heating conduits may be discharged directly into the scrubbing tower, the heating furnaces may be arranged and operated, in general, as described in this mentioned application. The

application filed -ing tower following the refining tower, may be returned to the scrubbing tower as' described in an Number 257,945, by Arnold G. Vobach.

In carrying out the invention in the apparatus illustrated, the heating furnaces. 2a and 2b are controlled so that the oil stream flowing through the heating conduit 1a is heated to a higher temperature therein than is the oil stream flowing through the heating conduit 1b.

In the production of motor fuel gasoline, for example, the heating furnace 2b may be controlled so that the hot oil products are discharged from the heating conduit 1b at a temperature in the neighborhood of 1080-l120 F. and the heating furnace 2a may be controlled so that the hot oil products are discharged from the heating conduit 1a at a temperature in the neighborhood of 11301l70 F.

Fractionating towers 4 and 5 may be controlled by means of either or both of the reflux condensers 17 and 18 or 19 and 20. Raw stock may be circulated as a cooling medium, being at the same time preheated, through reflux condensers '17 and 19. Some extraneous cooling medium such as water reflux condensers .18. and 20. Fractionating tow ers 4 and 5 may also be controlled by means of the direct introduction of raw stock through connections 21 and 22, or by means of such introduction of raw stock supplemented by the operation of one or more of mentioned. v

In the production of motor fuel gasoline, for example, the fractionating tower 4 may be controlled so that the temperature of the vapors escaping through connection 15 approximates F. and the fractionating tower 5 may be controlled so that the temperature of the vapors escaping therefrom approximates 375-4 50 F.

The scrubbing tower 3 may be controlled by the reflux condensers just meansof the reflux condenser 23 or by the direct introduction of raw stock through connection 24 or by means of such introduction of raw stock y the operation of the reflux consupplemented denser.

The condensate separated in the first fractionating tower 4 is supplied to the heating conduit February 29th, 1928, Serial' may be circulated through 1b through connections 25 and 11 by means of pump 26 and the condensate separated in the second fractionating tower 5 is supplied to the heating conduit 1a through connections'27 and 10 by means of pump 28. A part of this latter condensate may be discharged through connection 29.

Raw stock, particularly raw stock including tar or pitch constituents, may be supplied to the scrubbing tower 3 through connection 24, the high boiling oil components of such stock being vaporized in the scrubbing tower to be condensed in one or the other of the successive fractionating towers 4 and 5 to be supplied therefrom to the connected heating conduit lb or 1a respectively. Relatively higher boiling raw stock corresponding .to the condensate separated in the fractionating tower 4 or raw stock including lower boiling constituents may be supplied to the fractionating tower 4 through connection 21. Raw stock corresponding to the condensate separated in the fractionating tower 5 may be supplied to the fractionating' tower 5 through connection 22. The same raw stock may be supplied through both connections 21 and 22 where the raw stock supplied does not include any substantial amount of constituents higher boiling than suitable to be supplied to the heating conduit 1a. The fractionating tower 5 is with advantage controlled so that the escaping vapors condense to form a distillate product of the desired boiling range or, if the fractionating tower I is used, of somewhat broader boiling range including a limited proportion of higher boiling constituents.

I claim: 4

In the cracking of hydrocarbon oils, the improvement which comprises flowing two separate streams of oil through twoseparate heating conduits and heating each stream of oil to a high cracking temperature in the vapor phase therein, one of said oil streams being heated to a higher temperature than the other, subjecting the hot oil products discharged from the two heating conduits to a common scrubbing operation for the separation of tar, separately supplying liquid oil to and withdrawing tar from the scrubbing operation, subjecting the vapors from the scrubbing operation to successive first and second fractionating operations, condensing a-cracked distillate from the vapors escaping from the second fractionating operation, supplying the condensate from the second fractionating operation to the heating conduit in which the oil stream is heated to the higher temperature, supplying the condensate from the first fractionating operation to the other of the two heating conduits, and preventing 'retum to either of said heating conduits o tar withdrawn from said scrubbing operation.

WILLIS S. GUILE'I'I'E. 

